Power tool

ABSTRACT

In a power tool in which a disc-shaped tool is attached to a spindle that protrudes from a housing, a dust-collecting cover provided on the housing for covering the disc-shaped tool has a tool insertion opening. A rotation stopping tool that stops rotation of the spindle can be inserted into the dust-collecting cover through the tool inserting opening. The duct-collecting cover is provided with a rubber ring that blocks the tool insertion opening such that the opening can be opened and closed as desired.

BACKGROUND OF INVENTION

This application claims the benefit of Japanese Patent ApplicationNumber 2011-079521 filed on Mar. 31, 2011, the entirety of which isincorporated by reference.

1. Technical Field

The present invention relates to a power tool including adust-collecting cover that covers a disc-shaped tool attached to aspindle, and collects dust produced when a workpiece is machined.

2. Background Art

A grinder disclosed in Japanese Patent Application Publication No.2011-56641 includes a spindle that is rotated by a motor housed in ahousing, a disc-shaped grinding tool attached to the spindle, and adust-collecting cover that covers the periphery of the grinding tool.Generally, the grinder grinds a workpiece by moving the rotatinggrinding tool on the workpiece while keeping the grinding tool incontact with the workpiece. Dust produced during grinding is collectedin the dust-collecting cover, and then discharged from a dust-collectingtube that communicates with the interior of the dust-collecting cover,into a dust collector, via a suction hose.

In a power tool as represented by the above-described grinder, thedust-collecting cover has a tool insertion opening through which arotation stopping tool, such as a spanner, can be inserted into theopening of the cover. When a lock mechanism for stopping rotation of thespindle fails, rotation of the spindle can be stopped by means of therotation stopping tool inserted through the opening formed on the cover.However, in the dust-collecting cover having the tool insertion opening,the inside and outside of the dust-collecting cover communicate witheach other via the tool insertion opening, and the air tightness withinthe dust-collecting cover is reduced. Accordingly, efficiency of dustcollection in the dust-collecting cover is reduced.

On the other hand, if the tool insertion opening is closed all the timeso as to ensure air tightness, as the rotation stopping tool cannot beinserted into the dust-collecting cover, the spindle does not stoprotating when the lock mechanism for the spindle fails.

SUMMARY OF THE INVENTION

This invention is proposed in view of the above situation, and it is anobject of the present invention to provide a power tool in which dust iscollected in a dust-collecting cover with enhanced efficiency, androtation of a spindle can be stopped using a rotation stopping tool.

According to a first aspect of the present invention, there is provideda power tool which includes a housing, a motor housed in the housing, aspindle that protrudes from the housing, a disc-shaped tool attached tothe spindle, a dust-collecting cover that is provided on the housing,and covers the disc-shaped tool, and a tool insertion opening that isformed in the dust-collecting cover, and enables a rotation stoppingtool that stops rotation of the spindle to be inserted into thedust-collecting cover. In the power tool, the dust-collecting cover isprovided with an opening and closing member that blocks the toolinsertion opening such that the tool insertion opening can be opened andclosed as desired.

In the power tool according to a second aspect of the present invention,in the first aspect of the present invention, the opening and closingmember may be a ring-shaped rubber member that is mounted on thedust-collecting cover and blocks the tool insertion opening.

In the power tool according to the first aspect of the presentinvention, the opening and closing member blocks the tool insertionopening formed in the dust-collecting cover, and therefore, the airtightness of the dust-collecting cover is improved. Accordingly, theefficiency of dust collection in the dust-collecting cover can beenhanced. If the tool insertion opening is rendered open to thedust-collecting cover, using the opening and closing member, therotation stopping tool can be inserted into the dust-collecting cover,through the opened tool insertion opening, so as to stop rotation of thespindle.

When the tool insertion opening is blocked by the ring-shaped rubbermember, the air tightness of the dust-collecting cover is improved, andthe efficiency of dust collection in the dust-collecting cover can beenhanced. Further, when the rubber member is rolled up, the toolinsertion opening of the dust-collecting cover appears, and the rotationstopping tool can be inserted into the dust-collecting cover through thetool insertion opening, so as to stop rotation of the spindle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view of a disc grinder as oneembodiment of the present invention.

FIG. 2 is a plan view of a dust-collecting cover included in the discgrinder.

FIG. 3 is a view explaining the time when rotation of a spindle of thedisc grinder is stopped.

DETAILED DESCRIPTION OF THE EMBODIMENT

One embodiment of the present invention will be described with referenceto FIG. 1 through FIG. 3. A disc grinder 1 shown in FIG. 1 includes ahousing 10 and a dust-collecting cover 20. The housing 10 consists of amotor housing 11 and a gear housing 15, The disc grinder 1 is oneexample of power tool of the present invention.

The motor housing 11 is formed in a cylindrical shape, and a motor M ishoused in the motor housing 11. A rotary shaft 12 of the motor M isrotatably supported in the motor housing 11 via a bearing 13, and afirst bevel gear 14 is provided at a distal end of the rotary shaft 12.

The gear housing 15 is mounted to the front (the left-hand side inFIG. 1) of the motor housing 11, and the rotary shaft 12 supported inthe motor housing 11 protrudes into the gear housing 15. In addition, aspindle 16 is rotatably supported in the gear housing 15 via bearings17, 18, to extend in a direction perpendicular to the rotary shaft 12. Asecond bevel gear 19 is mounted on an upper portion of the spindle 16.With the first bevel gear 14 engaging with the second bevel gear 19,rotation of the rotary shaft 12 is transmitted to the spindle 16. Thelower end of the spindle 16 protrudes downwardly of the gear housing 15,and an external threaded portion 16A is formed on an outercircumferential surface of a lower end portion of the spindle 16, In thedisc grinder 1, a disc-shaped grinding tool (not shown) is sandwichedbetween an inner flange and a lock nut screwed on the external threadedportion 16A, and is thus attached to the spindle 16. The disc-shapedgrinding tool is one example of disc-shaped tool of the presentinvention.

As shown in FIG. 1 and FIG. 2, the dust-collecting cover 20 includes amain cover 21, an auxiliary cover 22, a plate 23, a holder portion 24,and a rubber ring 26. The main cover 21 and the auxiliary cover 23 areformed of resin, and the main cover 21 is provided at its upper surfacewith an insert hole 21A through which the spindle 16 can be inserted.The auxiliary cover 22 is detachably or removably attached to the maincover 21. In a condition where the auxiliary cover 22 is attached to themain cover 21, the dust-collecting cover 20 assumes a generallybowl-like shape that has a larger diameter than the disc-shaped grindingtool and is open downwards, and surrounds the periphery of the grindingtool. A dust-collecting tube 21B that communicates with the interior ofthe main cover 21 is provided on the outer surface of the main cover 21.A dust collector can be connected to the dust-collecting tube 21B via asuction hose.

The plate 23 is made of metal, and is fixed to the upper surface of themain cover 21 by means of four screws 23A. The plate 23 is formed withan opening 23B that communicates with the insert hole 21A of the maincover 21. The holder portion 24, which is made of metal and has anannular shape that is concentric with the opening 23B, is formedintegrally with the upper surface of the plate 23. By fitting the holderportion 24 on a lower end portion of the gear housing 15 and fasteningit with a screw 24A, the duct-collecting cover 20 is coupled to the gearhousing 15.

As shown in FIG. 1 and FIG. 3, a tool insertion slot 24B is formed in abase portion of the holder portion 24 in the vicinity of the boundarybetween the plate 23 and the holder portion 24. The tool insertion slot24B is used for inserting a spanner 25 into the dust-collecting cover20. Further, the rubber ring 26, which has a flange portion 26A (seeFIG. 3) provided at its lower end portion and extending in radialdirections, is fitted along the outer circumferential surface of theabove-mentioned base portion. As shown in FIG. 1, the rubber ring 26,which is in close contact with the outer circumferential surface of thebase portion, normally blocks the tool insertion slot 24B, and theflange portion 26A, which is in close contact with the upper surface ofthe plate 23, closes a clearance between the rubber ring 26 and theupper surface. The rubber ring 26 is one example of ring-shaped rubbermember of the present invention.

Next, the operation of the disc grinder 1 will be described. Whengrinding a workpiece with the disc grinder 1, the operator holds themotor housing 11, and turns a switch ON so as to drive the motor M tooperate the dust collector. The grinding tool that rotates with themotor M thus driven is moved on a worked surface of the workpiece whilebeing kept in contact with the worked surface, so as to grind the workedsurface. Dust produced during grinding of the worked surface is suckedand collected from the duct-collecting tube 21B into the dust collectorvia the suction hose. At this time, the rubber ring 26 blocks the toolinsertion slot 24B, and the flange portion 26A closes the clearancebetween the rubber ring 26 and the upper surface of the plate 23;therefore, the inside and outside of the dust-collecting cover 20 do notcommunicate with each other, and the dust-collecting cover 20 is sealedwith improved tightness. Accordingly, the dust is prevented fromscattering out of the dust-collecting cover 20, and the dust-collectingefficiency of the dust-collecting cover 20 is enhanced.

In the meantime, if a lock mechanism for stopping rotation of thespindle 16 fails when a worn grinding tool is to be replaced by a newone, for example, the rotation of the spindle 16 needs to be stopped bya spanner 25. In this case, the rubber ring 26 is rolled up so that thetool insertion slot 24B is open to a surface of the dust-collectingcover 20, as shown in FIG. 3. Then, as shown in FIG. 3, the spanner 25is inserted into the dust-collecting cover 20 through the tool insertionslot 24B, to be engaged with a chamfered portion formed on the spindle16, so as to stop rotation of the spindle 16. The spanner 25 is oneexample of rotation stopping tool of the present invention.

EFFECT BY THE EMBODIMENT

In the disc grinder 1 of this embodiment, the rubber ring 26 blocks thetool insertion slot 24B, so that the dust-collecting cover 20 is sealedwith improved tightness. As a result, the efficiency with of dustcollection in the dust-collecting cover 20 can be enhanced. Also, byrolling up the rubber ring 26, it is possible to open the tool insertionslot 24B to the dust-collecting cover 20. Then it becomes possible toinsert the spanner 25 into the dust-collecting cover 20 through the toolinsertion slot 24B, and stop rotation of the spindle 16 with the spanner25.

The present invention is not limited to the above-described embodiment,but may be embodied by changing a part of the construction as needed,without departing from the principle of the invention. For example, therubber ring 26 may be replaced by an O ring made of rubber, and the Oring may be fitted along the outer circumferential surface of theabove-mentioned base portion, so that the O ring blocks the toolinsertion slot 24B.

Unlike the above-described embodiment, an opening and closing plate thatis rotatable in the vertical direction via a hinge member, for example,may be mounted on the holder portion 24, and the tool insertion slot 24Bmay be blocked by the opening and closing plate, such that the toolinsertion slot 24B can be opened or closed as desired. With thisarrangement, dust can be collected in the dust-collecting cover 20 withenhanced efficiency, and the rotation of the spindle 16 can be stoppedby the spanner 25, as in the above-described embodiment.

As a further example, a rubber magnet that is detachably attached to theholder portion 24 may be provided, in place of the above-describedrubber ring 26, for blocking the tool insertion slot 24B such that thetool insertion slot 24B can be opened or closed as desired. In thiscase, too, dust can be collected in the dust-collecting cover 20 withenhanced efficiency, and the rotation of the spindle 16 can be stoppedby the spanner 25, as in the above-described embodiment. The opening andclosing plate and the rubber magnet are examples of opening and closingmember of the present invention. While the present invention is appliedto the disc grinder in the above-described embodiment, the applicationis not limited to this example, but the present invention may also beapplied to a power tool, such as a sander or a cutter having adust-collecting cover.

It is explicitly stated that all features disclosed in the descriptionand/or the claims are intended to be disclosed separately andindependently from each other for the purpose of original disclosure aswell as for the purpose of restricting the claimed invention independentof the composition of the features in the embodiments and/or the claims.It is explicitly stated that all value ranges or indications of groupsof entities disclose every possible intermediate value or intermediateentity for the purpose of original disclosure as well as for the purposeof restricting the claimed invention, in particular as limits of valueranges.

1. A power tool comprising: a housing; a motor housed in the housing; aspindle that protrudes from the housing; a disc-shaped tool attached tothe spindle; a dust-collecting cover that is provided on the housing,and covers the disc-shaped tool; and a tool insertion opening that isformed in the dust-collecting cover, and enables a rotation stoppingtool that stops rotation of the spindle to be inserted into thedust-collecting cover, and an opening and closing member provided on thedust-collecting cover for opening and closing the tool insertion openingsuch that the tool insertion opening can be opened and closed asdesired.
 2. The power tool according to claim 1, wherein the opening andclosing member is a ring-shaped rubber member that is mounted on thedust-collecting cover and blocks the tool insertion opening.
 3. Thepower tool according to claim 2, wherein the dust-collecting coverincludes a main cover having an insert hole through which the spindlecan be inserted, a plate fixed to an upper surface of the main cover andformed with an opening that communicates with the insert hole, and aholder portion having an annular shape that is concentric with theopening and formed integrally with an upper surface of the plate so asto be coupled to the housing, wherein the tool insertion opening isformed at around a base portion of the holder portion in the vicinity ofa boundary between the plate and the holder portion.
 4. The power toolaccording to claim 3, wherein a flange portion that extends in radialdirections is formed at a lower end portion of the rubber member, andthe rubber member is fitted on an outer circumferential surface of thebase portion so as to block the tool insertion opening, while the flangeportion is in close contact with the upper surface of the plate.